Traffic light accessory



E. G. MAIN TRAFFIC LIGHT ACCESSORY March 11, 1952 Filed Oct. 7. 1949 INVENTOR EVERETT G; MAlN ATTORNEYJ Patented Mar. 11, 1952 TRAFFIC LIGHT ACCESSORY Everett G. Main, Ann Arbor, Mich., assignor to Main Flo-Control Traffic Light, Inc., Ann Arbor, Mich., a corp-cration of Michigan Application October 7, 1949, Serial No. 120,187

cessory which will indicate the comparative amount of time during which the green light of a traflic signal may be expected to remain illuminated.

Traflic lights presently in use comprise a red light which demands that the flow or vehicle and pedestrian traflic'should stop, and a green light which allows the same traiilc to proceed across an intersection. Most of the traffic lights in use also have an orange light which is illuminated at the end of the time that the green light is running and prior to the flashing on of the red light.

At the present time there is no equipment in use on traific lights which gives the driver of a vehicle adequate warning as to the amount of time remaining in the cycle in which the green light is illuminated, and many motorists are caught approaching an intersection at the allowed maximum speed and are forced to stop suddenly upon the lights changing without warning. Also, adequate warning systems are not in use to indicate to a pedestrian the time remaining in which he may safely cross a street with the green light so that he will not risk being caught in the stream of flowing trafllc which starts abruptly upon the signals being changed.

This situation is even more critical to the driver of a heavy truck which requires considerable space for braking, even under the most advantageous conditions, and which may become uncontrollable under conditions in which the road is wet or slippery. The situation reaches its worst at intersections of major highways outside community areas, where a trafiic signal suddenly turns from green to red in the face of the driver of a passenger automobile or a truck which is traveling at the higher speed allowed in rural The problem is complicated by another factor, in that it has been found advantageous to vary the time of displaying the green light and the red light on two highway or roadway intersec- 1 cross street requires that the green light be illuminated for the more heavily traveled thorough fare a much longer time than the green li ht is illuminated for the side street. This factor makes it impossible to use a very simple timer, and by reason'of the fact that the system must be infinitely variable, requires the use of devices such as that which is the subject of my invention.

;It is, therefore, anobject of this inventionto provide an indicator for use with a traillc light,

the indicator to show at a glance the comparative 2 amount of time remaining in which the green light will be illuminated.

A further object is to provide a traffic light which has the usual red and green lights, and a time indicator, the operation of the time indicator being coordinated with the operation of the green light.

A further object is to provide an indicator of the type described which is controlled by devices which are variable, in order that a cycle of any pre-determined length may be obtained.

Further objects and advantages of my invention will be apparent from a consideration of the following specification in connection with the appended claims, and the accompanying drawings, in which:

Fig. I is a View in elevation of the front of a traflic signal light upon which is mounted an accessory constructed in accordance with my in vention.

Fig. II is a side view of my device, partly in elevation and partly in section, with certain parts omitted and other parts diagrammatically displayed for clarity, and

Fig. III is a top plan view with certain parts omitted and others shown diagrammatically.

In the drawings, the traflic signal I9 is shown enclosed in the usual casing l2 having a top cover l4, and with a red light IS, an orange light l8 and a green light 20. The accessory 22 may be enclosed in any kind of a frame casing 24 suitably attached by known means to the casing l2, and presenting a lens 26 in a plane substantially parallel to the plane of the lights l6, l8 and 20. It will be appreciated that the lens 26 may be either clear glass or frosted glass, and in colors or colorless, depending upon the particular lamp used and the eiiect desired.

Mounted in a position substantially parallel to the longitudinal axis of the lens 26, and behind the same, is a light source 28 which is preferably a fluorescent 0r neon type tube, or some similar tubular lamp of the gaseous type. This light source 28 is backed by a reflector 39, preferably parabolic in cross section, the same being mounted within the casing 24 in any conventional manner.

Gaseous tubular lamps, such as fluorescent or neon, have the peculiar property of emitting light only over the area between two energized electrodes. My invention takesadvantage of this factor by utilizing a tube 23 employing multiple electrodes so that I may control the area or portion of the tube 28 which is light-emitting at any particular time.

As more plainly appears from Fig. II, the current for energizing the tube 2%! comes from the terminal block for the green li ht 20 through the conductors 32 and 34, and to the transformer 36.

The lead 38 from the transformer 36 is permanently attached to the electrode 40 adjacent the lower end of the tube 28. The lead 42 is connected to the rotor 44 and current passes through the contact points 46 on the contactor plate 48, and selectively through the leads 58 to the multiple electrodes 52. The electrodes 52 may be of the conventional type, or may be of the ring type which cause the current to flow through the material acting as a casing for the tube 28.

It will be appreciated that with such an electrical connection, the electrode 40 at the lower 1:

end of the tube 28 will be continuously energized, and that the multiple electrodes 52 may be selectively energized according to the movement of the rotor 44 in making and breaking contact with the contact points 46 on the contactor plate 48. Therefore, when the terminal block for the green light 20 furnishes current through the leads 32 and 34 to the transformer 36, the electrode 40 and the top-most multiple electrode 52 are energized and the entire tube will emit light. Then, as the rotor 44 selectively engages the contact points 46, it is possible to energize other of the multiple electrodes 52 in descending order down the tube 28, thereby successively shortening the column of light emitted from the tube 28. As viewed in Fig. I, the lens 26 will then emit light in a continuously shortening column as the time in which the green light 20 is expended, which change will give an appearance somewhat like a thermometer in which the indicating column is successively growing shorter.

It will be appreciated that, with the construction shown, it is possible initially to energize only a small portion of the tube and then to energize larger portions of the tube so that the light column will increase in length rather than decrease. This may be accomplished by changing the position of the various leads 50, or by reversing the direction of rotation of the rotor 44.

It may be desirable, under certain installations, to provide mens for controlling the brilliancy of the tube 28, especially during the time when some of the lower of the electrodes 52 are energized. If the installation is powered so that suflicient brilliancy is obtained when the topmost electrodes are energized and the tube is completely alight, it may be found that, as the light is shortened down the tube 28, the brilliance will increase to such a point that it becomes objectionable, or that the life of the tube is considerably shortened by reason of the destruction of the electrodes.

To provide a variable control which will fix the amount of time, required by the cycle, to

60 from the terminal block for the green light.

In other Words, when current is transmitted to illuminate the green light, the synchronous motor 54 is immediately started in operation. The shaft 62 of the motor 54 is fitted with a small disc 64 which engages the larger disc 66 mounted on the shaft 68 of the rotor 44. The shaft 68 is supported preferably by the mounting which is fitted with bearings not shown. It will then be appreciated that, as current is supplied through the terminal block for the green light to the leads 58 and 60, the synchronous motor 54 will be energized, which will turn the small disc 64 and rotate the disc 66 and the rotor 44.

By making the contactor plate 48 circular in form, and distributing the contact points 48 around its circumference, it will be appreciated that one revolution of the rotor 44 will accomplish the complete cycle required, and will at the same time position the rotor 44 for the start of a new cycle.

To provide means for adjusting the speed at which the rotor 44 makes its circuit of the contactor plate 48, I have provided an adjusting screw I2 which can be used to move the small disc 64 toward or away from the center of the disc 66, thereby determining the amount of time necessary for the synchronous motor to turn the disc 66 and the rotor 44 through one complete trip around the contactor plate 48.

In operation, then, it will be understood that when electrical current is supplied to the terminal block for the green light 20 through the ordinary timing mechanism for the green light, current will be supplied to the electrode 40 and the upper most of the multiple electrodes 52, :thereby lighting the tube 28. At the same time, current will be supplied to the synchronous motor 54 which will move the rotor 44 through one complete circuit of the contactor plate 48, thereby selectively de-energizing and energizing the multiple electrodes 52 in order from the top of the figure as shown in Fig. II down to the bottom. When the green light 20 is turned off, and if the system is properly adjusted, the rotor 44 will have made exactly one complete rotation around the contactor plate 48, and the light in the tube 28 will be extinguished at precisely the time that the ght 20 is extinguished. It will also bring the synchronous motor 54 to a stop and will leave all of the parts in position for the starting of the next cycle. a

Having described my invention, what I claim as new and desire to protect by Letters Patent is:

1. In combination with a go and stop traffic signal having a source of electrical energy supplied to the go signal. at intervals of predetermined duration, an accessory traffic signal directly associated with said go signal and energized by the same source of electrical energy as said go signal during the same intervals, said accessory signal being in the form of an illuminated column having illuminating means of progressively diminishing length, means for operating said illuminating means in seriatim during the period of operation of said go signal including an electric motor energized only during the period said go signal is energized from said source, and an adjustable drive mechanism between said motor and said second means to synchronize said accessory signal with the duration of operation of said go signal whereby the remaining portion of the duration of operation of the go signal during any given interval of operation is visually indicated.

2. In the combination of the claim 1, said electric motor being of synchronous construction.

EVERETT G. MAIN.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,602,444 Naiman Oct. 12, 1926 2,020,610 Johns Nov. 12, 1935 2,101,697 Watson -Dec. 7, 1937 2,117,639 Watson May 17, 1938 2,480,290 Fein Aug. 30, 1940 

